The original code for Processing.js used regular expressions to convert Java into JavaScript when it was encountered. It did this by scanning for hints of Java code within the entire sketch and then replaced the Java code with its JavaScript equivalent. Due to the difference in how Java and JavaScript accessed object properties from methods inside an object, the with statement was used as a simple solution to avoid having to prepend all function calls with "this." or "Processing.". However, the use of the with statement also meant that the JavaScript generated would fall off Trace /*cite trace paper here... do we need to talk about trace in the back ground section???*/ making the code run slower than it needed to in some browsers. Later this method of scanning the entire sketch was replaced by the creation of an abstract syntax tree that broke up the code into smaller pieces. Each piece then had the regular expressions applied to change it. This made it was easier to apply the regular expressions correctly without accidentally converting code that was already working. It also made it easier to create proper inheritance structures and attach properties and methods to the correct object in the hierarchy chain as smaller pieces of code was being converted at any one time.

==3D support==

===Problems===

WebGL provides a close match to OpenGL for incorporating 3D into Processing.js, but it does present some issues when trying to port over code. There are interface differences, changes to the interface are common, and some functionality isn't available at all such as point smoothing.

==Conclusion==